The present invention relates to an apparatus and a method for inspecting solid drugs for the detection of the presence of foreign matter on the solid drugs by scanning the surface of each solid drug item by the use of a television camera and generating a pulse signal when the level of a video scanning signal thereof exceeds a predetermined value.
More specifically, the present invention relates to the inspection of the surface of each solid drug item by inspecting the pulse signal bridging between the neighboring addresses in each scan line of the television camera and/or between the neighboring scan lines of the television camera and detecting the presence of foreign matter of a length and width corresponding to an output thereof.
Solid drugs such as tablets and pills are usually a compacted pharmaceutical preparation containing one or more powdery medicaments. It is often found that some of the solid drug items have indentations on the surface because of the containment of particles and some of them have attached thereto fibrous foreign matter originally included in one or more constituent medicaments and/or fibrous foreign matter such as hairs and/or textile fibers floating in the air.
As is well known to those skilled in the art, medicines should in no way contain foreign matter contained therein or adhering thereto and, even though they are prepared and manufactured under a controlled atmosphere, no complete elimination of the possibility of foreign matter adhering to and/or contained in the solid drugs can be possible. Specifically, of foreign matter, hairs are that which purchasers and patients dislike most and which often constitute a major cause of the blackened reputation of the manufacturer. Since the manufacture of medicine requires the intervention of many people, the inclusion and/or adherence of hairs can not be completely eliminated. The hairs tending to adhere to, or to be contained in, medicine are very fine in most cases, and therefore, it has long been desired to detect the presence of hairs, so fine as to be smaller than 100 micrometers, in the solid drugs by the use of an inspecting machine and, then, to eject the solid drug items, found to have the hairs, from the production line. It is pointed out that even hairs of about 50 micrometers in thickness are noticeable because they have length.
Hitherto, those solid drug items having such foreign matter have been removed from the inspection line as defective products. The inspection and the removal are carried out by the intervention of human labor, specifically the naked eyes and hands of one or more inspectors, and therefore, such problems as associated with errors in inspection and/or the departure from the inspection standards can hardly be avoided. This in turn results in the fact that the solid drugs often fail to satisfy the requirements concerning the surface precision to such an extent as to bring about the unpleasant sensation to those who are administered such solid drugs. In view of this, the automation of the inspection line has long been expected.